EP1901137B1

EP1901137B1 - Linear fusing nip zone

Info

Publication number: EP1901137B1
Application number: EP07116662.3A
Authority: EP
Inventors: Mark Steven Amico
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 2006-09-18
Filing date: 2007-09-18
Publication date: 2014-01-15
Anticipated expiration: 2027-09-18
Also published as: US7471923B2; US20080124145A1; JP2008077081A; EP1901137A1

Description

TECHNICAL FIELD

Embodiments are generally related to image processing. Embodiments are also related to the field of nipping mechanisms. Embodiments are additionally related to linear fusing in nipping mechanisms.

BACKGROUND OF THE INVENTION

Processes and devices have been used for image processing in which a nipping mechanism can be applied to an image processing apparatus which is being represented by electro photographic copiers, laser printers or facsimile machines. A nipping mechanism is usually provided in a fixing device disposed downstream from a transfer belt for transporting a sheet having a toner image transferred through a photosensitive drum. A nipping mechanism comprises a fixing roller having a heater embedded therein, and a pressure roller disposed in opposed relation to the fixing roller while allowing the lower portion thereof to be in close contact with the fixing roller.
In such an electrographic apparatus generally a fixing device in a two-roll system composed of a heating roll and a pressure roll, that is being kept in contact with each other, is employed passing through the recording medium over the surface. An unfixed toner image can be formed through the nip zone. A nip zone is formed when the recording medium is in contact with both rolls. Then the toner in the electrographic apparatus is molten by heat and pressure so that the toner image is fixed on the surface of the recording medium as a permanent image. As the case may be in place of the heating roll and pressure roll, the heating member of each has an endless belt shape.
As xerographic imaging systems continue to increase in speed, the need to provide an adequate nip width to a fuser toner and then to a media also increases. Referring to FIG. 1, labeled as prior-art, a graph 100 illustrates traditional roll pairs. The graph shows that traditional roll pairs are limited due to a relationship between roll diameters, elastomer thickness, and the available load. For example, to achieve a 30ms (milliseconds) dwell time when a 100ppm (pulse position modulation) rate is required, a nip width of 14.04mm (millimeters) is required. As speeds increase to 150ppm, an equivalent nip grows to 21.06m. At 200ppm the nip width is 28.08mm. In the graph the load (pounds) 102 defines the horizontal axis and dwell time (ms) 104 defines the vertical axis. The graph also shows the representations in specific values 106 when plotted.
Hence there is a need to provide an adequate nip width to a fuser toner by using a nipping mechanism. As xerographic imaging systems continue to increase in speed, a nipping mechanism with fusing enhancement that can be used in image processing for providing improved performance is needed. Ideally the sheet nipping mechanism and nipping mechanism for fixing devices can be enhanced by using a method of linear fusing in nipping mechanism.
US 5,319,429 describes color image forming apparatus using fixing apparatus for glossy images. A color image forming machine such as a copier or a printer for producing a toner image, corresponding to an original image, on a recording sheet. The color image forming machine has a photoreceptor for forming the toner image on its surface; a transferrer for transferring the toner image from the photoreceptor to the recording sheet; and a fixer for fixing the toner image on the recording sheet. The fixer includes an endless heat belt which is supported by a heat roller and a separation roller; and an endless conveyance belt which is supported by a pressure roller and another separation roller; in which the endless heat belt and the endless conveyance belt are partially pressed together by the first pair which are inclined relative to one another, and the second pair so that a nip region is created between the first pair of rollers and the second pair of rollers. The endless heat belt and the endless conveyance belt have a glossy surface. The fixer conveys the recording sheet upwards in the apparatus when the fixer fixes the toner image on the recording sheet.
US 6,226,474 B1 describes air impingement post fuser receiver member cooler device. A device for cooling receiver members after image fixing by the fuser assembly in an electrographic reproduction apparatus wherein a marking particle image is fixed to a receiver member with application of heat by the fuser assembly, the receiver member traveling along a transport path. The cooling device includes an upper housing and a lower housing respectively associated with the receiver member transport path, on opposite sides thereof, immediately downstream, in the direction of receiver member travel along the transport path, of the fuser assembly. The upper and lower housings respectively have transport path guide plates for guiding receiver members along the transport path. A plurality of ports defined in the upper housing transport path guide plate provide flow communication of pressurized air from a pressurized air source to the transport path, and a plurality of ports in the lower housing transport path guide plate provide flow communication of pressurized air from the pressurized air source to the transport path. Accordingly, air impingement for forced air provides convection cooling of receiver members traveling along the transport path and such air impingement also provides for transport of the receiver members via an air bearing thereby substantially preventing the receiver members from contacting the upper and lower guide path plates.
US 2006/0127142 A1 describes image heating device. An image heating device comprises a first belt which heats an image on a recording material at a nip, a second belt which forms the nip with the first belt, a first pressure member and a first rotating member which press the first belt at the nip, the first pressure member and the first rotating member being provided while not being in contact with each other; and a second pressure member and a second rotating member which press the second belt at the nip, the second pressure member and the second rotating member being provided while not being in contact with each other. The nip is formed by a region where at least one of the first pressure member, the first rotating member, the second pressure member, and the second rotating member is in contact with the corresponding belt.
JP 2004117518 A (Patent Abstract of Japan) describes heat fixing device and image forming apparatus having the same. The heat fixing device is provided with: a fixing belt unit having a tension means which applies specific tension to an endless fixing belt according to a variable distance between a reference fixing roller and an adjustment fixing roller; a pressure belt unit having a tension means which applies specific tension to the endless belt according to a variable distance between a reference pressure roller and an adjusting pressure roller; and a nip amount adjustment means which automatically adjust the positions of the adjustment fixing roller and adjustment pressure roller in accordance with image forming conditions.
JP2006178119 A (Patent Abstract of Japan) describes fixing device and image forming apparatus. In the fixing device, a toner image is fixed by supplying a recording medium to which an unfixed toner image is transferred to a nip part between a part of the outer peripheral surface of an annular film member made to circulate in a direction and a pressure roller arranged on the outside of the film member, and the film member and the recording medium are separated from each other at a medium separation part on a more downstream side in the direction A than the nip part, then a backing member supporting the inner periphery side of the film member at the nip part is formed in surface shape going along the surface a of the pressure roller. The fixing device is provided with a tubular heating element for heating the film member at a more upstream position in the direction than the nip part N.

SUMMARY OF THE INVENTION

It is the object of the present invention to improve a nipping mechanism for an image forming apparatus. This object is achieved by providing a nipping mechanism for an image forming apparatus according to claim 1 and a method for providing a nipping mechanism for an image apparatus according to claim 3. Embodiments of the invention are set forth in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the embodiments and, together with the detailed description, serve to explain the embodiments disclosed herein.
FIG. 1, labeled "prior art", illustrates a graph representation showing traditional roll pairs with reference to load and dwell time used for nipping mechanisms.
FIG. 2 illustrates a perspective view of an image forming apparatus of a linear fusing nip zone, in accordance with a preferred embodiment.
FIG. 3 illustrates a block diagram of a linear fusing nip zone, in accordance with a

preferred embodiment.

FIG. 4 illustrates a sectional view with the usage of two opposing flat air bearings to create a linear nip of a linear fusing nip zone, in accordance with a preferred embodiment.
FIG. 5 illustrates a high-level flow chart showing the functionality of a linear fusing nip zone, in accordance with a preferred embodiment.

DETAILED DESCRIPTION

The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment and are not intended to limit the scope thereof.
Referring to FIG. 2, illustrated is a perspective view 200 of an image forming apparatus of a linear fusing nip zone, in accordance with a preferred embodiment. The tracking rollers 202 are placed in context with the linear air bearing surface plates 204.
Referring to FIG. 3, illustrated is a block diagram 300 of a linear fusing nip zone, in accordance with a preferred embodiment. In this system paper enters 310 into an image forming apparatus with the help of an entrance roller 312. The entrance roller 312 is configured and set with two opposing unheated flat air bearing surface plates 204 for creating an extended linear zone. The flat air bearing surface plates provide a zero media-bend zone for fusing. Each flat air bearing surface plate is supported by one or more springs, or force loading devices 316, thereby providing the load required for achieving proper image performance when an image is being processed. The belt placement unit 304 includes two independent non-permeable belts for creating the fusing nip zone. The belts are controlled by belt tracking motion 306 and belt tensioning motion 308. The heater rollers 302 and a tracking roller 202 are shown in contact with the belts for heating and running the belt when printing is being done. The heater rollers 302 are ideally positioned to directly heat the surface of the side of the belt that comes into contact with paper during linear fusing nip zone operation. Although heat rollers 302 are shown, it should be appreciated that the rollers do not need to be heated and that another heat source, such as a heat lamp, could be used to heat the surface of the belts that comes into direct contact with the medium (paper). The exit roller 318 acts as an output interface through which the printed paper is sent out of the image forming apparatus of a linear fusing nip zone.
Referring to FIG. 4, illustrated is a sectional view of a nipping mechanism 400 using two opposing sections. The design encircled by the dashed line 404 is located below a mirror image of components that make of the upper section of the nipping mechanism. In accordance with the embodiment, flat air bearing surface plates 204 create part of a linear nip of a linear fusing nip zone. A nipping mechanism 400 uses two opposing unheated flat linear air bearing surface plates 204 to create an extended linear zone wherein two independent non-permeable belts 301 travel between thereby creating the fusing nip zone. The belts 301 are controlled by belt tracking motion control 306 and by belt tensioning motion control 308 over tracking rollers 202. The heater rollers 302 and tracking rollers 202 are set for running the belts 301 when printing is being done in an image forming zone created between the outside surface of belts 301 within the linear fusing nip zone. During operation, paper 310 can enter into the processing unit with the help of the belts 301 and entrance rollers 312. The entrance rollers 312 are further configured and set with two opposing unheated flat air bearing surface plates 204 and thereby create an extended linear zone. The loading operation in the image forming apparatus of a linear fusing nip zone moves in tandem to enable jam clearance 402 in-between the entrance rollers 312 and the linear flat air bearing surface plates 204.
Flat air bearing surface plates 204 provide a zero media-bend zone for fusing. These flat air bearing surface plates 204 are appropriate for highly loaded applications. Each flat air bearings plate 204 can be supported by one or more springs, or force-loading devices, thereby providing the load required for achieving proper media handling and performance through the system 400. The force-loading device provided by the combination of rollers and belts 301 provide a means for removing any tolerance stack-ups and parallelism issues in an image forming apparatus of a linear fusing nip zone. The exit rollers 318 act as an output interface through which the printed paper is sent out of the image forming apparatus of the linear fusing nip zone.
Fusing of images onto paper can be more effective using the embodiment shown in FIG. 4 because the belts 301 are heated directly on their outer surface by a heat source such as the heater rollers 302, before the belts 301 come into direct contact with paper within the fusing nip zone. Other heat source can be used to accomplish heating of the outer surface of belts 30, such as a heat lamp and other heat source known in the art. Heated rollers, however, are ideal because less heat is generated within the system housing by direct contact with heated rollers as opposed to a radiating heat source. In prior art devices, heat is generated on the belt using a heat source located opposite the contract surface of the belts 301. Heat applied to the backside of a belt, opposite the contacting surface of the belt, relies on heat transfer to warm the contact surface, which is a less efficient way to heat a belt and also results in unwanted heat generation within the overall system compartment or housing.
Referring to FIG. 5, illustrates a high-level flow chart 500 showing the functionality of a linear fusing nip zone, in accordance with a preferred embodiment. As depicted at block 502, initialization can occur. Next, as indicated in block 504, two opposing unheated flat air bearing surface plates are utilized to create an extended linear zone. Flat air bearing surface plates provide a zero media-bend zone for fusing and are appropriate for highly loaded applications as indicated in block 506. Thereafter as described in block 508, each flat air bearing surface plate is supported by one or more springs or force loading devices. The load required for achieving proper image performance is provided to the flat air bearing surface plates by the one or more springs or force loading devices as indicated in block 510. Force loading devices can also be used for providing a means for removing any tolerance stack ups and parallelism issues as depicted in block 512. Flat air bearing plates are incorporated in the system to provide a stiff, linear and a non-frictional plane which can be scaled to required widths and lengths for achieving the desired dwell time and process width as described in block 514. An extended linear nip zone is further created where two independent non permeable belts travel between the flat air bearing plates with the assistance of entrance rollers and exit rollers as indicated in block 516. Finally, a heated fusing nip zone is created by application of heat to contact surfaces of the belts with heater rollers as indicated in block 518.

Claims

A nipping mechanism for an image forming apparatus, the nipping mechanism adapted to form a linear fusing nip zone, the mechanism comprising:
two opposing unheated flat linear surface plates (204);

two belts (301) independently routed outside one of said two opposing unheated flat linear surface plates (204) using a combination of rollers;
characterized in that
force loading devices (316) associated with each of said two opposing unheated flat linear surface plates (204), said force loading devices (316) providing a load required for said two flat linear surface plates (204);

at least one heat source (302) associated with each of said two belts (301), said at least one heat source (302) providing heat directly to a surface of said two belts (301) that will directly contact paper processed through the linear nip zone,

wherein said two belts and said opposing unheated flat linear surface plates (204) surrounded by said two belts (301) provide a stiff, linear, no-friction zone between the belts covering the length of the opposing unheated flat linear surface plates (204) to form said linear fusing nip zone between the belts, wherein

said two opposing unheated flat linear surface plates (204) are air bearing opposing unheated flat linear surface plates providing said no friction zone.
The image forming apparatus of claim 1, wherein said linear fusing nip zone is further defined by having and entrance defined by entrance rollers (312) operating within each of said two belts and an exit defined by exit rollers (318) operating within each of said two belts (301).
A method for providing a nipping mechanism for an image forming apparatus, comprising:
providing two opposing unheated flat air bearing surface plates (204) to create an extended linear zone;

supporting each unheated flat air bearing surface plate (204) with force loading devices (316), wherein loads required for achieving proper image performance is provided to the flat air bearing surface plates (204) by the force loading devices (316);

creating an extended linear nip zone by providing two independent belts (301) configured to travel between the flat air bearing plates (204) with the assistance of rollers including entrance rollers (312) and exit rollers (318) associated with each of said two independent belts (301);

creating a heated fusing nip zone by applying heat to external, contact surfaces of the two independent belts (301).